1. Field of the Invention
The invention relates to a sound source detecting system and sound source detecting method that detect a sound source on the basis of sounds collected by a plurality of sound collectors.
2. Description of Related Art
In a sound source detecting system, an ambient sound is collected by a plurality of sound collectors, and the location of a sound source (particularly, the travelling sound of a vehicle) is identified on the basis of an arrival time interval between the collected sounds. In the system described in Japanese Utility Model Application Publication No. 5-92767 (JP 5-92767 U), electrical signals output from a plurality of microphones arranged at a predetermined interval are converted into corrected electrical signals by removing frequency components in a low-frequency band and a high-frequency band with the use of a band pass filter from the electrical signals, power in a predetermined frequency band in which the feature of the travelling sound of a vehicle appears is calculated from the corrected electrical signals, it is determined that there is an approaching vehicle when the power level is higher than a predetermined value, and corrected electrical signals are converted into noise reduction signals by removing unnecessary noise components from the corrected electrical signals, a crosscorrelation between the noise reduction signals of the plurality of microphones is computed, and the approaching direction of the approaching vehicle is computed from an arrival time interval at which the correlation is maximum.
Incidentally, in the above described technique, it is possible to detect the direction of the approaching vehicle; however, other unnecessary noises, such as a sound emitted from a host vehicle (an engine, a cooling fan, and the like) and a construction site, are also detected. These noises impair detection of a required sound source, such as an approaching vehicle, so there are many erroneous detections and it is difficult to improve detection accuracy.